Soil microbial population as influenced by direct and residual effect of organic and inorganic sources of nutrients in cowpea- little millet cropping sequence

Field experiments were conducted during 2017-18 and 2018-19 in sandy loam soils of Tirupati (AP) to evaluate the direct and residual effect of organic and inorganic sources of nutrients on soil microbial population and yield of cowpea-little millet cropping sequence. Three levels of organic manures (no organic manure, FYM @ 5 tonnes ha-1 and poultry manure @ 2 tonnes ha-1 ) and 3 phosphorus levels (0, 40 and 60 kg P2O5 ha-1 ) applied to preceding cowpea and 3 graded levels of nitrogen viz., 0, 10 and 20 kg ha-1 applied to succeeding rabi little millet. Soil microbial population and yield of kharif, cowpea varied with manures and phosphorus levels. Poultry manure @ 2 tonnes ha-1 recorded higher soil microbial population and pod yield which was on par with application of FYM @ 5 tonnes ha-1 . Among the phosphorus levels, application of 60 kg P2O5 ha-1 resulted higher soil microbial population and pod yield of cowpea. Soil microbial population and grain yield of little millet was influenced by the residual effect of organic manures and phosphorus applied to preceding cowpea, as well as direct nitrogen levels applied succeeding little millet, where 20 kg N ha-1 resulted higher values of microbial population and yield compared to 10 kg N ha-1 and control. This study concluded that the application of poultry manure @ 2 t ha-1 and 60 kg P2O5 ha-1 to preceding cowpea and 20 kg N ha-1 to succeeding little millet increased the soil microbial population and yield in main and residual cropping compared to respective control.
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Soil microbial population as influenced by direct and residual effect of organic and inorganic sources of nutrients in cowpea- little millet cropping sequence